A beam profile of an optical beam has a significant impact on processing performance associated with material processing performed using the optical beam. For example, an optical beam with an annular beam profile can enable superior metal cutting. However, beam profiles of most fiber-delivered optical beams are relatively simplistic. For example, the beam profile may be a Gaussian or near-Gaussian profile for a low-beam-parameter-product (BPP) laser (e.g., a BPP of less than or equal to approximately 3 millimeters times milliradians (mm-mrad)) that can be used for processing thin sheet metal (e.g., sheet metal with a thickness of less than or equal to approximately 3 mm) using a tightly focused optical beam. As another example, the beam profile may be a top-hat (sometimes referred to as a flat-top) profile for a high BPP laser (e.g., a BPP of greater than approximately 3 mm-mrad) that can be used for processing thick sheet metal (e.g., sheet metal with a thickness greater than approximately 3 mm) using a larger beam. A spliced fiber may cause an optical beam to have a particular beam profile. The spliced fiber may include an input fiber, a twisted fiber, and a target fiber that are spliced together to form the spliced fiber.